Study on the Criterion of SMA Framework

Fromthe traditional pointof view, the criterion of framework forSMA(stone matrix asphalt) mix is thatVDRC(the voids in coarse aggregate on the dry rodded condition) must be larger thanVMix(the voids in coarse aggregate of mix). However, there are several facets, such as the compaction method, the measuring precision, and the density conversion for calculating the voids in coarse aggregate, which could cause system errors. Consequently inmany casesVDRCis always largerthanVMix, and the optimal gradation can not be realized. The test results showthat theVMixwhich is calculated with the bulk density measured by calipers is fairly reasonable. There is a turning point in the curve for theVMixversus the percentage of the fine aggregate passing the 4.75 mm sieve. It is feasible to use this turning point to evaluate the formation of coarse aggregate skeleton in a SMAmix.